A 3rd Generation Partnership Project (3GPP) based on a Wideband Code Division Multiple Access (WCDMA) radio access technique is being extensively deployed all over the world. A High Speed Downlink Packet Access (HSDPA), which may be defined as a first evolution of the WCDMA, provides a radio access technique with a competitive edge in the mid-term future to the 3GPP. However, as requirements and expectations of users and service providers are continuously increasing and development of competitive wireless access techniques is proceeding, a new technical evolution in the 3GPP is requested to ensure competitiveness in the future. The requirements include a reduction in costs per bit, an increase in service availability, the flexible use of frequency bands, a simple structure and an open interface, proper power consumption of user equipments, or the like.
In general, cell selection may be classified into an initial cell selection performed at an initial stage after power of a user equipment is turned on and a cell reselection performed for a handover or a neighbor cell measurement.
The reason for the user equipment to perform a cell reselection is to register itself to a network to receive a service from a base station. If the strength or quality of signals between the user equipment and a serving cell is degraded due to the movement of the user equipment, the user equipment reselects a different cell to keep its transmission quality.
There may be various types of criterion to perform cell selection, and cell selection may be performed according to priority for inter-frequency or inter-RAT (Radio Access Technology). The priority may be temporarily changed due to mobility of the user equipment and various other factors. Thus, it is required to reconfigure priority over time, rather than maintaining the same priority for the same frequency or the RAT.
Besides the priority for cell selection, there may be various validity factors that may temporarily change the validity according to factors such as an environment in the wireless communication system. There is a need for a method to control effectively operations of the validity factors such as extension or release of validity.